Beware of keying any but the TC4426 chip... The non-inverting TC4427 has its
two outputs overlapping as the volts drop below 12, whereas the 4426
develops a dead band between the two outputs when the Volts are low. This
aids soft(ish) keying.
What a combined inverting / non-inverting chip would do would probably be a
combination of both!
High-level keying of the supply with another big mosfet is my preffered
system these days, you can tailor the envelope any way you like.
73. Dave G3YXM.